Drag and drop word file into existing pdf

I used to be able to drag and drop word files into an existing pdf.  I don't recall the word or adobe versions when this process worked for me.

The computer I now use is installed with adobe 9 and MS office 2010.  When I try to drag and drop a word file into an existing pdf, it now tries to save a pdf version of the word document each time.  It has not become a very time consuming process.

Is there a setting that needs to be changed in office or adobe to allow the drag and drop feature?

Thanks in advance!